Wood finishing



April 4, 1944. E A LEHMAN 2,345,942

WOOD FINISHING Filed Jan. e, 1942 4 sheets-sheet 1 INVENTOR EDGAR A. ff/MAN ATTORNEY -Aprl 4, 1944. E. A. LEHMAN WOOD FINI SHING Filed Jan. 6, 1942 4 Sheets-Sheet 2 INVENTOR @5M A. LfHM/w BYQZM m. @um

ATTORNEY April 4, 19214.

E. A. LEHMAN 2,345,942

WOOD FINISHING Filed Jan. 6, 1942 4 Sheets-Sheew'; 3

INVEYNTOR. 21a/w Hmm/v .April 4, 1944 E. A. LEHMAN 2,345,942

WOOD FINISHING Filed Jan. e, 1942 4 sheets-sheet 4 A s.. is.

1/' W l Y .I INVENTOR.

`i f5 BY M4/P EMM/v Patented Apg. 4, 1944 AUNITED AsTA'riss PATENT OFFICE WOOD I'INISHING aan: A. Lehman. Mmmm Ina., anni in The American Foundry Equipment Company, Mishawaka, Ind., a corporation of Delaware Application .1mm-y s, raiz.' serial No. 425,129

' (c1. iig-39) 8 Claims.

This invention relate. to wood nmsmng, and more particularh to the etching and coloring of wood surfaces to produce various decorative effects.

The present applicationis a continuation-inpart of my application Serial No. 298,071, filed October 5, 1939, and entitled Process of forming omamented wood surfaces".

Decorators are constantly seeking to produce unusual and striking decorative surface effects on the wood walls of restaurants, stores, barrooms, playrooms, and on wooden furniture and novelties. Woods having an etched or weatherbeaten surface appearanceare sought in the decorative art but etched or weathered woods heretofore produced have lacked uniformity, color quality and durability.

An object of this invention is to provide an improved mechanical method for etching and coloring wood surfaces.

Another object of this invention is to provide an improved method of producing decorative wood surfaces which have the appearance of air weathered or sea weathered woods.

Another'object of this invention is to provide an improved method of producing striking surface effects on wood surfaces at high .production speeds and at low cost.

Another object of this invention is to provide a method of treating the surfaces of low-priced woods and lumber to enhance and decorate the surface thereof so as to make such woods highly acceptable 4for interior trim and panelling.

Another object of this invention isY to provide an improved method o f treating low-priced woods so that knots, cross-grain structures, and other normally objectionable surface characteristics are developed and transformed into a finished surface of marked beauty and-attractiveness.

Another object of this invention is to produce an improved finished wood product which is adapted for numerous and various purposes in the decorative arts.

Another object of this invention is to 'produce an improved decorative wood product which is strong and durable, and which has la striking surface appearance.

In' accordance with this invention, the surface of the wood stock is subjected to the wearing action of abrasives fired against the surface by a centrifugal blasting wheel in a manner to etch the surface so that the grain line and knot areas of the wood stand out or project in relief from the spring growth areas which occur between the grain lines of the wood. This result may be effected by centrifugally projecting relatively hard particles of abrasive material against the surface in predetermined quantities and at a predetermined velocity speed, so that the abrasive serves to gouge out or wear away the spring -V growth areas .of the wood to a greater degree than the summer growth or grain line areas and knot areas without weakening, splitting or otherwise appreciably reducing the strength or serviceability of the wood treated.

The abrasive projector preferably comprises a centrifugal abrasive throwing wheel designed to throw a fan-shaped stream of abrasive against the wood surface to be etched. The wheel is so arranged that the longitudinal axis of` the` fanshaped stream extends generally parallel to the wood grain. Where a moderate etching effect is desired, the abrasive control device associated with the wheel is adjusted to fire the abrasive vagainst the wood surface in a generally downwardly direction so that the head end of the fanshaped stream strikes the wood surface at a relatively obtuse angle, with the trailing end of the fan-shaped stream striking the wood surface at an oppositely inclined angle. Where a sharper and more deeply defined etching effect is desired. the control device associated with the abrasive throwing wheel is so adjusted that the fanshaped stream of abrasive strikes the wood surface at a relatively acute angle, with both the leading andtrailing ends of the fan-shaped stream inclined in the same general direction.

'I'he wood surface may be colored or stained by mixing with the abrasive particles fired against the wood surface a certain quantity of pigment or coloring material, which may comprise lamp black if a grayish weatherbeaten appearance is desired, or a colored paint pigment powder of the desired color if a color shadeis desired. The pigment becomes firmly deposited on the wood surface in varying degrees of density which are characteristic of the -wood growth so as to produce an attractive color shading to the treated wood surface. In this method of treatment it has been found that the harder summer growth grain line areas and knot areas retain more coloring pigment than 'the intermediate spring growth areas, so that striking and unusual color shading effects are produced. After the wood surface has been etched and pigmented by the blasting operation to the desired degree, the pigment is then bonded and firmly sealed in its blast deposited position by a transparent lacquer or coating which is sprayed onto the treated surface.

If a more delicate color tone is desired, it is preferable to irst etch the wood surface with clean abrasive particles so as to bring the grain lines and knot areas into bold relief without discoloring the natural fresh appearance of the wood. 'I'he desired color tinge effects are then produced by mixing a very fine but hard and clean granular material, such as carborundum powder, with the selected color pigment having the desired color. The fine granular particles a greater amount of pigment than the intermediate relatively softer spring growth areas so as to produce a surface shading which is in direct proportion to the .grain characteristics of the wood.

By mixing a selected green or blue pigment with the granular particles and centrifugally firing the mixture against the wood surface, a.

surface appearance which resembles sea or water weathered wood may be produced. It is obvious that the etched wood surface can be given otherv color eects by the use of other colored pigments, such as yellow, orange, blue, purple, brown, amber, or shades thereof. The pigment treated wood surface is then coated with a colorless lacquer or coating to firmly bond and seal the pigment to the etched wood surface as deposited by the blasting operation.

Various shaded color eects may also be achieved by projecting relatively dry pigment powder of the selected color tone transversely of the wood grain at a relatively low angle so that the pigment becomes deposited on the etched surface in varying degrees. The pigment may be deposited so thatone side of the raised grain projections receives the full force of the pigment blast, giving this side of the grain projections a relatively dense color tone while the opposite side of the grain projections receives a minor quantity of pigment so that the surface presentsa different color appearance depending upon the angle at which it is viewed. Various different color tones and color effects can thus be created depending upon the angle at which the pigment is blasted against the etched grain lines of the wood.

By following my improved method of wood treatment, low-priced inexpensive woods, such as commonly used for boxing, crating and rough sheathing, may be transformed to present a iinished surface of marked beauty, and normally objectionable knots, cross-grain structures and other objectionable surface deformations and irregularities may be developed to further enhance the beauty and attractiveness of the 1inished surface so that such low-priced, heretofore considered inferior, woods may be used for iine interior trim and panelling.

Woods may be given various unusual and striking decorative effects at high production speeds and at low cost. by conveying the selected wood continuously through the abrasive blast projected by the centrifugal blasting wheel. Where weatherbeaten Wood surface effects are desired, a coloring pigment may be mixed directly with the abrasive employed in etching the wood. Where more delicate color eifects are desired, it is preferable to convey the selected wood through the abrasive blast of a centrifugal blasting wheel to first cleanly etch the wood surface Aand thereafter to 'convey the etched wood through the blast of a second abrasive throwing wheel firing coated with the selected color pigment. Shaded effects can be achieved by projecting the pigment against the etched surface at an acute angle. powdered form, the transparent lacquer can be immediately applied to the pigmented surface by spraying, without drying or further treatment.

Various other features and advantages of the invention willbe apparentA from the following particular description and from an inspection of the accompanying drawings.-

wood before treatment showing the natural grain hard and sharp but clean granular material 75 lines and knots therein;

Fig. 2 is a cross-section of the planed wood showing the grain lines emerging into the planed surface thereof, as it appears when looking in the directions of the arrows 2--2 of Fig. l;

Fig. 3 is a diagrammatic illustration of a centrifugal blasting wheel showing the manner in which the etching abrasive or pigment-coated granular particles may be thrown from the periphery of the wheel to bombard the planed surface of the natural wood to produce a medium 4etching effect;

Fig. 4 is a magnified cross-section of the wood surface in the process of being etched by the abrading action of abrasive particles, the abrasive particles being shown,coated with'a selected pigment to stain the etched surface;

Fig. 5 is a plan view of the wood section as it appears after being etched and stained by the pigment coated abrasive particles thrown from the periphery of the centrifugal blasting wheel illustrated in Fig. 3;, y

Fig.6 is a cross-section of the wood showing the manner in which the grain lines project in bold relief from the etched surface of the wood and as they appear when looking in the direction of the arrows 6 8 oi.' Fig. 5;

Fig. 7 is a magnified fragmentary cross-section of the etched and pigment treated wood surface after it has been coated with a transparent lacquer which bonds and cements the pigment .deposit onto the etched surface of the wood;

Fig. 9 illustrates a number of hard carrier granules greatly magniiied, sonic of which are shown in cross sections and others coated with the selected coloring pigment;

Fig. 10 is a magnified cross-section of the etched wood surface as it appears after treat- ,ment with pigmented carrier granules which serve to deposit the selected color pigment on the etched surface in varying densities which vary with the wood grain;

Fig. 1l is a magnified cross-section of the etched wood surface shown in'Fig. 9 after the pigmented surface has been coated and bonded by a transparent lacquer coating;

Fig. 12 is a` diagrammatic illustration of a cen- Since the pigment usedjs in dry and assauts trifugal blasting wheel positioned to ilre the etching abrasive at a low or acute angle against the wood surface to further emphasize and increase the depth of the etch: Fig. 13 is a magnified top plan view of the wood surface when deeply etched by the abrasivefired at an acute ,angle from the abrasive throwing wheel adjusted as illustrated in Fig. 12;

Fig. 14 is a cross-section of the wood showing the deeply etched surface as it appears when viewed along line il-Il of Fig. 13;

Fig. 15 is a diagrammatic illustration of a irl!- mentary portion of a blast nozzle arranged to project dry pigment transversely against the etched grainv of the wood at a relatively acute angle so that a greater quantity of pigment is deposited on one side of the grain line projections than on the other side thereof Fig. 16 is a top plan view of the etched wood surface after it has been subjected to the pigment blast directed at an acute angle-transversely against the grain projections as illustrated in Fig. 15; and

Fig. 1'? is a cross-sectional view through the etched and 'pigmented wood shown in Fig. 16 after a transparent lacquer coat has been applied thereto.

Similar reference characters refer to similar parts throughout the several views of the drawings and the specication.

The summer growth and knot areas of wood are generally harder than the intermediate spring growth areas so that when the wood surface is subjected to abrasive bombardment the spring growth areas will wear away more quickly than the summer growth areas. By subjecting the wood surface to abrasive bombardment, the wood surface may be etched so as to bring out the summer growth grain lines and knots in bold relief with the intermediate spring growth areas depressed below the top surface of the summer growth and knot areas.

" In order that this. invention may be more clearly understood, there is shown in Figs. 1 and 4 2 a short section of wood i having a planed sursince these grit sizes permit high production speeds without tearing or splintering the wood! Round steel shot, preferably varying in size from No. 30 to No. 22, colnparable to grit sizes No. 60 to No. 38, may also be used if s. peaned or mottled surface effect is desired. By a selected mixture of both grit and round shot, various etched as well as mottled surface effects may be produced which are striking and unusual in appearance and useful in various decorative schemes. Where a medium depth etching' effect is desired, the abrasive may be thrown from the abrasive projector wheel I0 in the manner illustrated in Fig. 3. The direction of fire of the fan-shaped stream is controlled by adjusting the control cage so that any desired angle of impingement can be achieved. Where the fan-shaped stream portrays an abrasive pattern as illustrated in Fig. 3 with the longitudinal axis 0f the pattern extending in the direction of the grain, a medium depth etching eifect can be obtained. If a deeper and more sharply defined etch is desired, the control cage of the abrasive throwing wheel may be adjusted so as to direct the abrasive along the run of the grain at a substantially acute or low angle. as illustrated in Fig. 12. Thus varying etch characteristics can be obtained by changing the angle of impingement of the abrasive against the wood surface being treated.

Where the wood surface is to be given a weather-beaten appearahce, the coloring pigment may be mixed directly with the etching grit or shot. Where'a blackish weather-beaten effect is desired, ordinary steel abrasive grit or shot v may be used particularlywhere any iron dust wood is subjected to'bombardment by abrasive I particles thrown from a centrifugal blasting wheel lengthwiseof the grain at velocities suiliclent to etch out or wear away the summer growth areas l to a predetermined depth and thus bring out the summer growth grain line areas i and knot areas 5 into bold relief.

The abrasive material selected to perform the etching operation is preferably sharp metal grit, such as steel grit, preferably of rather coarse size.

` 'I'he steel grit preferably used may vary from what is known as No. 60 grit to No. 38 grit, No. 45 grit having been found to be a useful average. No. 60 grit would be retained on a screen having openings of .013 inch but would pass through a screen having'openings of .025 inch. No. 38 steel grit will be retained on a screen having openings of .032 inch but will pass through-a screen having -openings of .0416 inch; and No 45 grit will be retained on a screen having openings of .024 inch and will pass through a screen having openings of .030 inch. While finer grits than No. 60 grit may be used in the etching operation, it has been found that grits ranging between No. 60 grit and or rust dust deppsits in the grit or shot will blend in with the desired color effect to be produced on lthe wood. Where the etched wood `surface is to be given alighter color tone', such as yellow, orange, blue, green. red, purple or amber, it is preferable to use clean and polished abrasive grit or shot which does not impart any discoloring effect to the wood surface being etched. Since the abrasive shot or grit may substantially all be recovered for re-use and does not become appreciably broken through the bombardment action, a high grade polished grit or shot may be used without appreciably adding to the production cost.

The abrasive grit or shot is fed into a bladed centrifugal blasting wheel diagrammatically illustrated in Figs. 3 and 12 and designated with .the numeral l0. A centrifugal blasting wheel which I have successfully used for this purpose is illustrated in Unger Patent No. 2,162,139, and it embodies a bladed wheel or rotor in which the blades extend inwardly short of the axis of rotation of the wheel or rotor to provide a central space into which a normally stationary apertured control cage is positioned. xA bladed impeller is positioned within the control cage and is fixed to the wheel or rotor so as to rotate with the blades thereof. The abrasive Y grit or shot is fed into the central opening of the impeller andfis thrown by the impeller blades or vanes through the aper No. 38 grit are most useful for etching the wood. `75 In performing the etching operation the abraproximately 12,000 feet per minute.

found that the time consumed in performing the etching operation on normal woodsv greatly increases at speeds 'lower than 9,000 feet per minute. While lineal speeds which exceed 12,000 feet per minute may. at times be used, it has been found that velocity speeds substantially in excess of 12,000 feet per minute may result in undesirable splintering o1' the etched surface.

I have successfully used a standard size abrasive throwing wheel of the type shown in Unger Patent No. 2,162,139 to perform the etching operation, which standard wheel has a diameter of approximately 19% inches with blades approximately 25/2 inches wide. This wheel was'rotated at from 1800 to 2400 R. P. M., producing a peripheral velocity of from approximately 9,000 to ap- It will be appreciated that my improved etching operation can be carried out with an abrasive throwing wheel of any convenient size if rotated to develop the required peripheral abrasive throwing velocity, and one or more etching wheels may be employed to produce almost any desired production speed. If relatively shallow etched effects are desired, the abrasive throwing wheel may be rotated at reduced speed or the wood to be .treated passed through the abrasive stream at a correspondingly higher speed. It has been found that a highly satisfactory etching effect can be obtained when from 5 to 15 pounds of steel grit abrasive is flred at from 9,000 to 12,000 feet per minute against each square foot of wood surface treated. Thus a satisfactory etching eil'ect has been produced when a standard size abrasive throwing wheel is rotated at approximately 2250 R. P. M., throwing 300 to 400 pounds of steel grit abrasive per minute, with the wood surface moving through the fired stream approximately eight to twelve inches from the wheel `periphery at speeds from fifteen to sixty feet per minute.

Where the wood surface is to be given an old and weather-beaten appearance, it has been found that the selected coloring pigment 6, such as lamp black pigment producing a blackish or grayish tint, or brown or amber paint pigment producing a brownish tint, may be mixed with the abrasive particles 1 in sufficient amounts to coat the abrasive particles with the pigment powder, as shown in Fig. 4. Where lamp black is used it has been found that one pound of lamp black thoroughly mixed with 400 pounds of abrasive particles imparts a highly satisfactory blackish or grayish weather-beaten tint to the wood. Where a brown or amber pigment is used a greater amount of the pigment should be mixed with the abrasive particles, the amount of pigment used being determined by the color strength desired.

The pigment coated abrasive particles 8-1 above described are fed into the center of the centrifugal Blasting wheel and are thrown from the wheel I0 when rotating at peripheral velocities of from approximately 4,000 to 14,000 feet per minute. While the wheel may itself be advanced over the wood surface to be treated, it is preferable to x the rotating abrasive throwing wheel at one point and advance the wood surface at a continuous uniform speed through the blasting stream, the speed of advance varying with the coatedabrasive per minute is employed, the surface of the wood may be satisfactorily etched as indicated by the numeral 2' so as ,to bring the.

summer growth grain lines and knots into bold relief to give the wood a wcatherbeaten appearance when .the wood surface is advanced through the abrasive stream at from forty to sixty feet per minute. Any desired surface area maybe etched by providing a number of abrasive throwing wheels arranged in staggered orV echelon arrangement and any desired production speed can be obtained by employing the required number of abrasive throwing wheels.

Where the etched` surface 2' is to be given tinta of more delicate color, such as a greenish, bluish, reddish, purplish or orange tint, it is preferable to first etch the wood surface with clean and polished shot or grit so thatthe abrasive will not 'discolor the etched surface. Such clean and pol- -face and prevents discoloration thereof.

The cleanhardshotlmaybeiiredatthesaine velocity to effect the desired etching of the wood surface as the pigment-coated shot or grit O-'I illustrated in Fig. 4 and above described. To give the etched wood surface the desired color tint, the cselected color pigment ll as shown in Pig. 9 is mixed with a fine but clean and hard granular material I2, which is fired against the wood surface by a centrifugal blasting wheel, such as the blasting wheel illustrated in Unger Pat. No

2,162,139. The granular carrier material used in y pigmenting or staining the etched wood surface 2" should be clean and hard and relatively fine.

Granular material which I have found highly adaptable for this Purpose is aluminum oxide or silicon carbide, 'preferably having aneness of 80 mesh or finer. It will be appreciated, however.

that other hard, clean and sharp carrier particles l may be used for this purpose, such as polished quantity of pigment-coated abrasive particles or clean metal abrasive grit.

The powdered pigment Il of the selected colorl is mixed with the granular carrier particles I2, as shown in Fig. 9, so as to thoroughly coat the hard granular particles. The pigment powder Il will adhere to the surface of the granular particles I2 and coat the same as indicated in Fig. 9 where some of the pigment-coated carrier particles are shown greatly magnified and are shown in cross-section to more clearly reveal the pig- `ment coating. -The pigment selected may be ordinary paintlor stain pigment the desired color, such as. brown, amber, gray, red. yellow. blue, violet or shades thereof. Y

'Ihe amount of pigment powder which is mixed with the granular carrier particles determines the color density or tone of the finished surface. To obtain a relatively light tone, for example,v approximately one pound of colored pigment is mixed with approximately pounds of the granular carrier particles, such as aluminum oxide particles. Where a relatively solid tone is desired, the pigment powder can be greatly increased, up to cne'pound of pigment to approximately five pounds of granular carrier particles.T

The color depth or tone of the nished etch surface can be varied within wide limits by properly proportioning the pigment powder and granular carrier mixture. For example, I have found that approximately 25 pounds of granular carrier material, such as aluminum oxide particles, mixed with one pormd of blue or green pigment will produce a highly satisfactory bluish or greenish quality to the etched surface which resembles water weathered or green wood. Where the lighter or pastel shade pigments are employed. a greater percentage of such pigment should be added to the granular material to emphasize the color tone.

The pigment-coated carrierV particles lI-l2 are fed into the bladed centrifugal throwing wheel which may be similar to the throwing wheel Il. For performing the pigmentlng operation I. have successfully an abrasive throwing wheel 2,162,139 mentener a peripheral velocity or ap- 4,000 to 14,000 lineal feet per minute, with velocities ranging from approximately 9,000 to 12,000 lineal feet per minute having found this to be a useful average for mostv woods. However, the character and hardness of the wood surface, the depth of the etch andthe production speed desired are factors to be considered in determining the wheel velocity.v A smaller and lower capacity abrasive throwing wheel maybe employed for the pigmentlng operation as compared with the wheel employed for theetching operation, since a greatly reduced volume of pigment-coated granular particles is thrown to eifect proper pigmentation and staining of the etched surface than the volume of cutting abrasiveA required to etch the surface. For the pigmenting operation, therefore, I have successfully employed an abrasive throwing wheel of the type shown in the above referred to Unger patent, having a diameter of approximately 15 inches and a blade width of approximately one and one-half inch, equipped with the apertured control cage to direct the red material uniformly onto the wood surface'. The lower periphery of the pigmented wheel is spaced from ve to twelve inches from the etched surface of the wood. The pigment-coated granular material ll--IZ is fed into thevcentral impeller which rotates with the blades of the wheel but within the control cage. The pigmenting wheel having a diameter of approximately fifteen inches may be rotated at from 1,500 to 2,000 R. P. M. depending upon the character of the wood being treated and the strength of the color tone desired. For the treatment of most woods, a wheel of 15 inches diameter rotated at 1800 R. P. M. has proved satisfactory.

The pigment-coated granular particles, designated Ii-i2, are thrown at a velocity ranging from 4,000 to 14,000 lineal feet per minute so as to bombard the clean emhed surface 2" of the wood. The pigment material Il on the particles l2 is `larred from the carrier .particles by the impact and is deposited on the etched surface 2" of the wood as illustrated in Fig. in'varying density as indicated by il' in Figs. 10-11. The wood is preferably kept constantly moving under the pigmenting blast so that approximately one pound of pigment-coated granular material is thrown against approximately one square foot of the etched surface 2", which is usually sufficient 75 to produce an attractively shaded color tone.

However. the quantity of pigment-coated granularmaterialthrownagainstasquare footof.

etched surface may be varied substantially below or substantially above one pound of material per square ,foot of etched surface treated, depending upon the color strenlth desired.V The abrasive throwing wheel should be so constructed that a substantial quantity of air is'permitted to flow into the wheel. It has been found that a vented hub wheel having an enlarged air admitting feed pipe of the type shown in Unger Pat. No. 2,162,139 successfully admits the desired quantity of air into the wheel. This air appears to serve a useful function in assisting the distribution of the pigment powder over the etched surface so that the pigment will be deposited with greater density on thegrainlineareas andtheknotareasof the wood than on the softer spring growth areas.

Thus the pigmented wood presents a shaded or subdue the grain lines and knots in accordance with the color tone of the pigment employed.

The etched surface may also be given a varying color tone by directing a blast of the powdered pigment transversely of the etched grain, as illustrated in Fig. 15. The pigment Il may be applied by an air blast nozzle l5 to which pigment and compressed air is supplied, or the pigment may be applied at the desired angle by a projector wheel of the type above described. The powdered pigmentv will cling to those surfaces of the etched wood which are in the direct line of the blast to a greater degree than the surfaces which are partially or wholly sheltered from the blast so that when the pigmented surface is viewed at one angle it will appear to have a relatively dense color coat and when viewed at an opposite angle will appear to have a relatively light color coat, and when viewed at still another angle the etched surface will have the appearance of highlights and shadows. While a major portion of the powdered Pigment'will be deposited on the raised surfaces of the' etched the powdered pigment so as to coat the etched surface in varying degree and the treated surface will differ in appearance according to the different angles at which it is viewed.

The spray nozzle i5 may form a part of the usual paint spraygun and, if desired, the pigment may be applied in the form of a liquid mixture rather than dry.

When the surface of the wood has been pigmented, as by mixing the pigment S with the etching abrasive l as illustrated in Fig. 4, or has been separately pigmented by the pigment H carried by the carrier granules I2 as illustrated in Fig. 9, thrown against the cleaned etched surface Z" by the pigmenting wheel, or has been pigmented by nozzle I5 as shown in Fig. 15, or has been clean-etched without pigment to reveal the clean wood. the etched surface is coated with a transparent lacquer 9 as illustrated in Figs. '1, 11 and 17. The lacquer preserves the etched surface and bonds the pigmenting material, if employed, to the surface of the wood. The transparent lacquerv coating can be conveniently applied by air spray.V It has been folmd that this method of application does not disturb the pigment deposit when the pigment deposit has been applied by a centrifugal blasting wheel in the manner above described. The pigment color which h been selected to either highlight or subdue the raised grain lines and knots is clearly visible through the transparent lacquer. The

transparent lacquer finish closes all wood pores and prevents the possibility. of'splinters developing in the wood surface.

A highly attractive ornamental wood. surface can be produ'ced by following the teachings of this invention which finds acceptable use by interior decorators for trimming and panelling room interiors, decorating wood furniture and wood novelties. The treated wood is substantially undamaged by the etchingoperation when carried out in accordance with this invention and it is substantially as serviceable and longlasting as the original wood before etching. The etching operation is so performed that splinters are not formed or developed, and the lacquer iinish serves to round oil the sharp edges so that the etched surface does not cut or injure the skin or clothing when rubbed thereover.

By following the treatment procedure above described, low-priced woods presenting surface knots. cross-grain structures and other normally objectionable deformations may be developed and enhanced to the point where such woods may be used for highly artistic interior trim and panelling where prime high-grade/ woods only have heretofore been used. Thus cheap and inferior quality woods, such as those which have heretofore been used for boxing, crating and rough sheathing, may be advantageously used for interior trim, panelling, furniture and wood nov- While certain nove) features of the invention have been disclosed herein, and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. The process of decorating wood surfaces having differential hardness areas which includes, mixing abrasive particles with a selected pigment powder to coat the abrasive particles with the pigment powder, and centrifugally projecting' the pigment coated abrasive particles against the wood. surface at a low angle with respect to the surface, so as to simultaneously differentially abrade and stain the wood surface.

2. The process of producing decorated wood -surfaces which includes, treating the-wood sur- 3. A woodproduct having a surface on which the natural grain lines and knots project Yin bold relief over depressed portions so as to form ridges, portions of said surface .having particles of pigment partially and directly imbedded therein, the density of said pigment deposit being greater on the projecting portions than on the depressed portions.

4.Awoodproductha'tingasurface onwhich the natural `grain lines and knots proiect in bold relief over depressed portions so as to form ridges, portions of said surface having particles of pigmentpartially and directly imbedded therein, the density of said pigment deposit being greater on the projecting portions, than on the depressed portions, and a transparent coating covering the pigmented portions of said surface to protect `the pigment deposit on the wood.

5. The process of decorating wood surfaces which includes projecting a blast of abrasive materialagainstthesurfacetobetreatedto wear the same away differentially to a depth depending on the diiferential density of the wood grain. and centrifugally projecting at a lowy angle with respect to the wood surface an abra sive mixed with a pigment against the differentially abraded surface unevenly to deposit the pigment thereon according to the surface contour created by the abrasion, whereby a stain pattern is produced emphasizing the grain structure of the wood.

6. The process of decorating wood surfaces which includes, treating the wood surface to obtain a raised grain, and blasting a pigment mixed with an abrasive against the surface at a low angle with respect to the wood surface. un-

evenly to deposit the pigment thereon accordingtothesurfacecontourpresentedbythe raised grain, whereby Vthe pigment is pounded intothewoodandastainpatternisproduced emphasizing the grain structure of the wood.

7. The process of decorating wood surfaces which includes, directing a blut of abrasive materialagainstthesurfacetobetreatedto abrade the same differentially to a depth depending on the differential density of the wood grain; and directing a blast of abrasive mixed with a pigment against the diiferentially abraded surface atarelative lowangletothesurfaceandsubstantiallytransversetothedirectionofthewood gram unevenly to deposit thereon according to the surface contour created by the abrasion whereby a shaded stain pattern is produced appearlnginlight anddarkshades dependingcn the direction from which it is viewed.

8. The process of decorating wood surfaces having differential hardness areas which includes, mixing abrasive particles with a selected pigment powder to coat the abrasive particles with the pigment powder, and projecting the pigment coated abrasive particles against the wood surface at a'low angle with respectto the surface, so as to simultaneously differentially abrade and stain the wood surface.

EDGAR A. mmm. 

